M. Wheldale 



373 



product formed he terms allocyanidin and he suggests that the reaction 

 proceeds as follows with the opening of the pyrone ring : 



HOi'^Y^ <( )>0H HO 



"°? t2H„ 



PH ^ OH /H 



OH °^^/C 



H„0 



Allocyanidin forms a crystalline compound with hydrochloric acid 

 and it is apparently on the analysis (by combustion) of this compound 

 that Willstatter bases the above constitution of allocyanidin. 



Allocyanidin chloride is unstable on heating in dilute hydrochloric 

 acid but when the crude solution from reduction of quercetin with 

 nascent hydrogen is diluted and heated in order to decompose allo- 

 cyanidin chloride the solution does not entirely lose colour owing to 

 the presence, according to Willstatter, of a small amount of a second 

 substance. The latter formed with hydrochloric acid a crystalline 

 product which on isolation and analysis proved to be identical with 

 cyanidin chloride. From 33 gms. of quercetin, 0"165 gm. only of the 

 product was obtained. The identity was established on the results of 

 analysis (by combustion), appearance, solubilities and properties in 

 general. It is suggested by Willstatter that the reaction proceeds as 

 follows : 



HO 



+-H.,0 



Since the constitution of quercetin is known, Willstatter considers 

 the formula for cyanidin chloride to be established by the above reaction 

 and very probably also the formulae for delphinidin and pelargonidin 

 clilorides : 



